package basic_class_01;

import basic_class_01.common.Utils;

import java.util.Arrays;

/**
 * 功能描述: 选择排序
 *
 * @param:
 * @return:
 * @auther: xujianfeng
 * @date: 2018/10/15 10:17
 */
public class Code_02_SelectionSort {


    public static void selectionSort(int[] arr) {
        int shortest = 2;
        if (arr == null || arr.length < shortest) {
            return;
        }
        for (int i = 0; i < arr.length - 1; i++) {
            int minIndex = i;
            for (int j = i + 1; j < arr.length; j++) {

                minIndex = arr[j] < arr[minIndex] ? j : minIndex;
            }
            //存在自己和自己交换的情况
            swap(arr, i, minIndex);
        }
    }

    public static void swap(int[] arr, int i, int j) {
        // 异位或的陷阱--如果相同的值交换，异或的函数中的第一步就会将自己置位0
        if (i == j ){
           return;
        }
        arr[i] = arr[i] ^ arr[j];
        arr[j] = arr[j] ^ arr[i];
        arr[i] = arr[i] ^ arr[j];
    }

    public static void comparator(int[] arr) {
        Arrays.sort(arr);
    }

    public static int[] generateRandomArray(int maxSize, int maxValue) {
        int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
        for (int i = 0; i < arr.length; i++) {
            arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
        }
        return arr;
    }

    public static int[] copyArray(int[] arr) {
        if (arr == null) {
            return null;
        }
        int[] res = new int[arr.length];
        for (int i = 0; i < arr.length; i++) {
            res[i] = arr[i];
        }
        return res;
    }


    public static void printArray(int[] arr) {
        if (arr == null) {
            return;
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }

    public static void main(String[] args) {
        int testTime = 500000;
        int maxSize = 100;
        int maxValue = 100;
        boolean succeed = true;
        for (int i = 0; i < testTime; i++) {
            int[] arr1 = generateRandomArray(maxSize, maxValue);
            int[] arr2 = copyArray(arr1);
            selectionSort(arr1);
            comparator(arr2);
            if (!Utils.isEqual(arr1, arr2)) {
                succeed = false;
                printArray(arr1);
                printArray(arr2);
                break;
            }
        }
        System.out.println(succeed ? "Nice!" : "Fucking fucked!");

        int[] arr = generateRandomArray(maxSize, maxValue);
        printArray(arr);
        selectionSort(arr);
        printArray(arr);
    }


}
